Aspen Journalism is compiling a data dashboard highlighting metrics of local public interest, updated at least weekly by mid-day Tuesday.

Warmer temperatures increase local streamflow

The USGS gauge on the Roaring Fork River near Aspen at Stillwater, located upstream of town, measured streamflow at 26.6 cfs on April 3, which represents 83.13% of average. A week before, the river was flowing at 25.1 cfs. On April 4, 2021, the river ran at 23.8 cfs.

The Roaring Fork’s streamflow level is below the minimum instream flow of 32 cfs established by a 1976 water rights decree but is higher than last year.

The Crystal River above Avalanche Creek, near Redstone, flowed at 148 cfs, or about 138% of average on April 3. The warmer temperatures of the last weekend of March kick-started the snow melting process and increased local streamflow. The Crystal jumped from 62 cfs on March 24 to 192 cfs on March 29, before going down to 132 cfs on April 1.

The USGS gauge on the Colorado River at Dotsero has recorded an increase in streamflow since March 24 when the river ran at 837 cfs. On April 3, the river was flowing at 1,360 cfs. The Crystal River at the CPW Fish Hatchery bridge ran at 83.5 cfs on March 24 before spiking at 229 cfs on March 29. The river was flowing at 186 cfs on April 3. That puts the river above the minimum instream flow set at 100 cfs set by the 1979 water rights decree.

Snowpack at Ivanhoe has gained nearly two inches since last week while warmer temperatures decreased snowpack at McClure Pass

“Snowpack in the Roaring Fork Watershed is currently 106% of normal, and snow and seasonal temperatures are in the forecast over the next week, which will help maintain our snowpack,” according to the Roaring Fork Conservancy’s snowpack report of March 31.

SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 85.3% of average on April 3, with a “snow water equivalent” (SWE) of 13.9 inches. The size of the snowpack relative to the 30-year average is the same as last week’s 85.3%. Last year on April 3, the SNOTEL station up the pass recorded an SWE of 14.61 inches.

The monitoring station at the lower-elevation McClure Pass recorded a SWE of 12.8 inches, or 77.1% of average, on April 3. A week before, the station reported 13.19 inches of water contained in the snowpack, or 80.9% of average. McClure Pass lost about one inch of SWE between March 27 and 29 when spring temperatures kicked in. Last year, on Apr. 3, the station measured a snowpack holding 12.01 inches of water, or 72.3% of average.

On the northeast side of the Roaring Fork Basin, snowpack at Ivanhoe contains higher water levels than the 1991-2020 average, with 16.61 inches on April 3, which is 109.3% of the average of 15.2 inches. It jumped from 15 inches of SWE on March 28. It’s also up from last year’s 15.31 inches of SWE.

Snowpack at Schofield Pass reached 36.8 inches on April 3, which represents 108.6% of average. Schofield Pass sits at an elevation of 10,700 feet between Marble and Crested Butte.

Snow water equivalent — the metric used to track snowpack — is the amount of water contained within the snowpack, which will become our future water supply running in local rivers and streams.

Lake Powell’s elevation keeps dropping

Lake Powell‘s storage reached its lowest level recorded since it began filling in the 1960s and ’70s on April 3 when the reservoir was 23.88% of full.

Last week, on March 27, the reservoir was 24% of full. The reservoir’s capacity has fallen since last year, when on April 3, 2021, the reservoir was 36.23% of full.

The surface elevation of Lake Powell dipped below the target elevation of 3,525 feet on March 15. The reservoir hit a record low on April 3 when its elevation dropped to 3,523 feet, or 177 feet from full pool. The reservoir had lost six inches since March 27, when the elevation was at 3,523.5 feet. Last year, on April 3, the reservoir reached 3,566.3 feet or 129.04 feet from full pool.

The “minimum power pool” for turbines generating hydropower at the Glen Canyon Dam is 3,490 feet, and 3,525 feet has been set as a buffer to ensure that the reservoir and the turbines can continue to function properly. Aspen Journalism recently published a story on the impact of last summer’s emergency releases designed to help Lake Powell.

Maximum air temperature increased 30 degrees in Aspen between March 22 and 27

Temperatures increased from a high of 34°F on March 22 to a high of 64°F on March 27, which is 17.6 degrees above normal, according to temperatures recorded at the Aspen/Pitkin County Airport. On March 30, maximum temperature dropped to 37°F before going back up to 51°F on March 31. The minimum decreased from 32°F on March 29 to 19°F on March 31. As of Apr. 1, the minimum reached 29°F, or five degrees above normal.

Aspen starts April with ‘clean’ air

The air quality in Aspen was “good” this past week. The AQI index for ozone ranged from 38 on March 29 to 47 on Apr. 1.

Laurine Lassalle is Aspen Journalism’s data desk editor, where she works to catalogue and analyze local public data. She also heads our our “Tracking the Curve” project, documenting COVID-19 in Pitkin,...